Its possible add buttons in toolstrip on left and right side, as image below show.
I try add css style but its not possible add style on image div.
PS. I create that effect using firebug.
Use a LayoutSpacer.
ToolStrip toolStrip = new ToolStrip();
...
toolStrip.setMembers(leftBtn1, leftBtn2, new LayoutSpacer(), rightBtn1, rightBtn2);
That will align first two buttons to left and other two buttons to right.